1. Field of the Invention
The present invention relate to a method of manufacturing a thin film transistor, a method of manufacturing a display substrate and a display substrate. More particularly, the present invention relate to a method of manufacturing a thin film transistor, a method of manufacturing a display substrate and a display substrate by using an oxide semiconductor.
2. Description of the Related Art
Generally, a thin film transistor used to actuate a pixel in a display apparatus includes a gate electrode, a source electrode, a drain electrode and an active pattern. The active pattern forms a channel between the source electrode and the drain electrode. The active pattern includes a semiconductor layer that has an amorphous silicon, a poly silicon or an oxide semiconductor.
When an amorphous silicon layer is used as the semiconductor layer, it has the advantage of forming uniformly. On the other hand, due to low electron mobility of an amorphous silicon layer, about 1˜10 cm2/V, the actuating property of the thin film transistor is low. Poly silicon, in contrast, has an electron mobility of that is tens to hundreds cm2/V better than the electron mobility of amorphous silicon. However, due to an essential crystallization process of the silicon when forming a poly silicon layer, poly silicon layers tend to form irregularly, and have high manufacturing costs. Oxide semiconductor layers, on the other hand, due to manufacturing by a low temperature process, easy upsizing and high electron mobility, are received attention from many technology areas.
However, the oxide semiconductor is easily damaged during the process of forming an input electrode and an output electrode of the thin film transistor that contacts the oxide semiconductor, and is very sensitive to the damage. Therefore, a property of the thin film transistor is declined. In such a process, an etch-stopper may be formed to minimize the damage of the oxide semiconductor. However, forming the etch-stopper increases the manufacturing cost.